The objectives of this research are to determine: a. the possible additive or synergistic effects on the central nervous system (CNS) resulting from the co-abuse of alcohol and diazepam; b. the effects of acute administration of alcohol on the CNS of animals maintained on subchronic diazepam; c. the effects of acute administration of diazepam on the CNS of animals maintained on subchronic alcohol; and d. the effects of acute administration of alcohol on subsequent discrimination learning by rats on subchronic diazepam. To address these problems, a match-sample discrimination task will be used with baboons as subjects, an auditory-visual 2-lever discrimination task will be used with rats as subjects and the Geller-Seifter conflict test will be used with rats. Data obtained from the baboon studies will reflect drug-induced cognitive deficits, while the data obtained from the rat studies will be a measure of the drugs' anxiolytic activities and effects on learning. In addition, tissue distribution studies will be conducted to provide data which might implicate alterations in bioavailability of one or both drugs or drug-induced changes in liver enzymes to account for the observed behavioral effects.